Combined plug and circuit breaker



May 23, 1950 J. D. BOLESKY COMBINED PLUG AND CIRCUIT BREAKER Filed May 22, 1948 /NVENTOR (JOHN D. BOLESKY 1477'0RNEY Patented May 23, 1950 COMBINED PLUG AND CIRCUIT BREAKER John D. Bolesky, Mansfield, Ohio, assignor to Adrian Medert, trustee, Cleveland, Ohio Application May 22, 1948, Serial No. 28,555

7 Claims.

This invention relates to plugs of the type employed in attaching an electric cord to an outlet, embodying an electric circuit breaker or switch, and more particularly to a plug having an automatic switch employing a bimetallic element responsive to excessive heat produced by current overloads for opening the switch contacts.

In switches of this general type the bimetallic element is normally so formed and mounted that when the contacts are closed and the current load is less than a predetermined amount the contacts will tend to remain closed, either due to a tension inherent in the bimetallic element or by means of a spring. When the current exceeds the predetermined value, the bimetallic element becomes overheated and moves from its normal position, in the well known manner, opening the contacts to break the circuit. After the contacts have thus been opened the bimetallic element may automatically return the contacts to closed position upon cooling of the element, or they may remain in the open position until closed by a manuall operated reset device. The present invention is concerned with the latter type and seeks to provide a simplicity of construction together with certain advantages not heretofore obtained.

It is among the objects of the present invention to provide a plug embodying a current overload responsive switch having manually operable reset means which are positive and direct acting for returning the contacts to closed position.

Another object of the invention is to provide in a plug a switch of the type described in which the contacts when closed are yieldingly held in such position by an over-center spring until opened by the action of the bimetallic element, and in which the contacts when open are yieldingly held in this position by the spring until closed by manually operated reset means.

Another object is to provide a plug embodying an automatic switch which must be disconnected from the outlet of the current supply to be reset, thus eliminating the possibility of inadvertent resetting and with the resultant restoration of current to the circuit before the cause of the current overload has been corrected.

Another object of the invention is to provide in a plug an automatic switch which is simple in construction, easy to manufacture, and which utilizes but few parts.

Other objects and advantageous features of the invention not at this time more particularly pointed out will become more apparent as the nature of the invention is better understood Figure 1 is a plan view with the top half of the plug housing removed and showing the contacts of the switch in open position,

Figure 2 is a view similar to Figure 1 except that the contacts of the switch are shown in closed position,

Figure 3 is a plan view with the top half of the plug housing replaced,

Figure 4 is an end view taken on the line 4-4 of Figure 3, and,

Figure 5 is a view of the opposite end and showlng the terminals for connecting the plug to a source of current supply.

With reference to the drawings, in the embodiment of the invention illustrated, numbers I and 2 indicate members of a plug housing which are made of a suitable non-conducting material and which may be accurately positioned upon one another by means of a rabbet 3. The housing members are complementally chambered and formed internally to receive the various parts of 2 the switch and are held together by means of bolts appropriately located.

Each of the housing members I and 2 is formed with a complemental recess 5 which when assembled define a chamber for receiving a terminal prong 6. The terminal prong 6 is attached at its inner end to one end of a flexible conducting member 1 which in turn is connected at its other end to a. conducting clip 8 mounted in a recess 9 of the housing members and which extends partially into the recess 5. The clip is provided with a binding terminal to which the end of lead I0 is secured by means of screw II. The screw ll also serves to anchor the clip 8 firmly to the housing member I. It will be noted that the recess 5 is of sufiici'ent width to permit the terminal pron 6 to be swung laterally to the position shown in dotted lines at 28 in Figure 2.

The housing members I and 2 are provided with a recess l2 separated from the recess 5 by the wall section I3. A second terminal prong It has one end anchored within the recess 12 and the other end projecting from the housing in parallel relation to the prong 6. The terminal prong M has a right angle portion Hi to which one end of a bimetallic element [5 is secured by means of angulated member lGa. The other end of the bimetallic element is attached to the free end of a leaf spring II. The opposite end of the leaf spring I! is pivotally mounted on a pin IS. A contact button (9 is united, preferably by brazaccess:

111:, to the bimetallic element ll intermediate the ends thereof.

Opposed to the contact button I! there is another contact button 20 suitably mounted on a conducting clip 2| located within a housing recess 22 with one end thereof extending into the recess l2 and the other end into housing recess 28. A binding terminal is provided on the clip II to which a lead 25 is secured by a screw 24. The end of the clip 2| which carries the contact 20 is preferably slightly yieldable so as to allow greater leeway in manufacturin tolerances and also to provide a slight followup when the contacts are being broken and a slight cushioning action when the contacts are being closed.

An additional recess 26 is provided in the housing members to accommodate the leads i and It, which pass therefrom through an aperture 21.

The wall section it has a transverse slot 28 therethrough in which a non-conducting pin 80 is slidably mounted so as to project into both recesses and i2.

The housing member 2 is formed in two sections, an upper section 2a and a lower section 2b. The lower section 222 covers the movable switch parts whereas the upper part covers the screws H and 24 to which the leads l0 and are attached. This arrangement is of advantage in that it is not necessary to uncover the movable switch parts when servicing the lead connections.

The plug operates in the following manner. The projecting portions of the terminal prongs are adapted to be inserted into a conventional electrical outlet, not shown, for connecting to a source of current. Lead wires l0 and 25 lead to the electrical device to which current is to be supplied. Under normal operation the contacts is and 20 are held closed (Figure 2) by the action of the over-center spring II, which in this position of the parts is biased in a direction to constantly urge the bimetallic element into contact-closing position. Current from the supply passes through the terminal 6, member 1, clip 8, and lead I0 to the device to be operated. The current returns through lead 25, clip 23, the contacts 20 and i9, bimetallic element l6, and terminal ll.

When for any reason more than an excessive amount of current is caused to flow, the heat produced thereby causes the bimetallic element l6 to arch in a manner to cause the end 3i thereof connected to the spring ll to pass to the right (as viewed in Figure 2) of the line between the spring support pin l8 and the lower end of the bimetallic element where it is secured to the right angle portion l5 of the terminal It, at this point the spring i'l snaps the bimetallic element It into the position shown in Figure 1, thus separating the contacts l9 and 20 and interrupting the ilow of current. After the bimetallic element has passed over center in this manner, the direction of bias of the spring H is changed so as to yieldably urge the bimetallic element in a direction for maintaining it in the open-contact position. The over-center spring will maintain the bimetallic element in the open-contact position even after the latter has cooled and until the element has been manually reset to the closed position.

To effect the reset, the terminals 6 and M are withdrawn from the outlet and terminal 8 is manually moved to the left to the dotted position as shown in Figure 2. This causes the bimetallic element, through the medium of the pin 30, to be moved to the position shown in Figure 2 closing contacts l9 and 20. The end portion 3i is now to the left of the line between the pin it and the lower end of the bimetallic element, and therefore the spring ll becomes biased in a direction tending to keep the contacts closed. Upon release of the terminal 8 it will return to its initial position. The terminals may then be reinserted into the current supply outlet and normal operation of the electrical device resumed.

Although I have shown and described but one embodiment of my invention it is obvious that many changes in detail construction may be made without departing from the scope of my invention as defined in the following claims.

I claim:

1. A plug embodying an automatic switch for protecting against current overloads comprising a non-conducting housing, a pair of terminals projecting from said housing, a pair of contacts within said housing for controlling the flow of current between said terminals, a current overload responsive element for opening said contacts, yieldable means for urging said element to either open or closed contact position, and means responsive to the lateral movement of one of said terminals for moving said element to closed-contact position.

2. A plug embodying an automatic switch for protecting against current overloads comprising a non-conducting housing, a pair of terminals projecting from said housing, a pair of contacts within said housing for controlling the flow of current between said terminals, a bimetallic element in series with said terminals and carrying one of said contacts, said element being responsive to excessive heat produced by current overloads ior opening said contacts, and means responsive to the lateral movement of one of said terminals for closing said contacts.

3. A plug embodying an automatic switch for protecting against current overloads comprising a non-conducting housing, a pair of terminals projecting from said housing and adapted to be connected to a source of current supply, one 0! said terminals being arranged for lateral movement, a pair of contacts within said housing for controlling the flow of current between said terminals, a bimetallic element in series with said terminals and carrying one of said contacts, said element being responsive to excessive heat produced by current overloads for opening aid contacts, and means requiring said terminals to be disconnected from said source of current supply to permit the lateral shifting of said terminal for returning said element to closed contact position.

4. A plug embodying an automatic switch for protecting against current overloads comprising a non-conducting housing, a pair of terminals projecting from said housing, one of said terminals being movably mounted laterally within said housing, a pair of contacts within said housing for controlling the flow of current between said terminals, a bimetallic element in series with said terminals and carrying one of said contacts, said element being responsive to excessive heat produced by current overloads for opening said contacts, and means responsive to the lateral movement of said movable terminal for returning said element to closed contact position.

5. A plug embodying an automatic switch for protecting against current overloads comprising a non-conductive housing, a pair of terminals projecting from said housing, one of said terminals being movably mounted laterally within said housing, a pair of contacts within said housing for controlling the flow of current between said terminals, a bimetallic element in series with said terminals and carrying one of said contacts, said element being responsive to current overloads for opening said contacts, and means operable upon lateral shifting of said movable terminal for returning said element to a closed contact position.

6. A plug embodying an automatic switch for protecting against current overloads comprising a non-conducting housing, a pair of terminals projecting from said housing, one of said terminals being movably mounted laterally within said housing, a pair of contacts within said housing for controlling the flow of current between said terminals, a bimetallic element in series with said terminals and carrying one of said contacts, said element being responsive to current overloads for opening said contacts, and non-conducting means operable upon lateral shifting of said movable terminal for returning said element to a closedcontact position.

7. A plug embodying an automatic switch for go rials being mounted for lateral movement within said housing, a pair of contacts within said housing for controlling the flow of current between said terminals, a bimetallic element in series with said terminals and carrying one of said contacts, said element being responsive to overloads for Opening said contacts, and a non-conducting pin slidably mounted within said housing and movable by said movable terminal into engagement with said element whereby said element may be returned to a closed-contact position.

JOHN D. BOLESKY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,191,501 Schmidt Feb. 27, 1940 2,399,406 Toth Apr. 30, 1946 2,429,784 Whitted et al Oct. 28, 1947 

